A terrifying, spider-like alien interrupts an amateur film crew‘s attempts to shoot a shoestring zombie movie in “Super 8,” investing a sweet, family-friendly drama with big-budget thrills. Rare is the writer-director capable of creating such compelling horror-movie characters, yet one suspects J.J. Abrams’ spirited teen ensemble would have sustained our interest even without the CG E.T. Sadly, the helmer seems too smitten working with Steven Spielberg to recognize that his idol-turned-champion created the very paradigm that limits his passion project, forcing this modest nostalgia trip to function as a blockbuster. What could have been a sleeper hit seems ill equipped to attract the broad summer audience its tentpole trappings demand.

Despite whatever bad blood exists between their parents, Joe can’t help being attracted to his pretty blonde classmate, which would be fairly generic stuff, if not for Abrams’ decision to set the romance against the production of a backyard monster movie. Joe isn’t the director but merely the makeup artist, leaving him to flirt with Alice while bossy best friend Charles (husky and equally charming newcomer Riley Griffiths) sets up the shot, serving as a less flattering stand-in for the helmer.

As a teenager, Abrams was enterprising enough for his filmmaking exploits to catch Spielberg’s eye, which earned the young prodigy a gig restoring Spielberg’s own 8mm homemovies. Three decades later, Abrams seems to be fulfilling a childhood dream, directing an elaborate homage to those early days under the Amblin banner. American directors are constantly paying tribute to the fertile ground that inspired their own careers (Woody Allen had “Radio Days,” Joe Dante made “Matinee”), but Abrams’ attempt is different in that he allows an ear-splitting, server-straining CG train crash to derail his rose-colored reverie, emerging with a relatively standard monster movie instead.

Had “Super 8″ opened in 1979, the year in which it’s set, one might have easily mistaken the film for the work of Spielberg, who had channeled his alien-invasion and suburban-family anxieties into “Close Encounters of the Third Kind” two years earlier. But even though Abrams leans heavily on many of his mentor’s stylistic signatures — lingering on the faces of awestruck kids, withholding the monster for as long as possible and transforming an all-American neighborhood through Klieg lights and crane shots, to name but a few — “Super 8″ owes at least as much to another picture hitting theaters that summer: Ridley Scott’s “Alien.”

The latter debt feels more subconscious, since Abrams doesn’t reference Scott’s dark, acid-dripping scarefest nearly so openly, and yet, in both temperament and scale, “Super 8’s” alien-on-the-loose indubitably shares a fair amount of that classic H.R. Giger-designed creature’s DNA. Still, despite an inspired explanation for why the beast is so hostile (hint: nurture, not nature), Abrams’ alien seems like an afterthought in a story that is far more invested in its six young human characters.

For one, “Super 8″ refrains from giving auds a good look at the giant, otherworldly arachnid until so late in the game that it forces our attention on the junior ensemble, who were selected carefully enough to hold their own onscreen (Gabriel Basso, Zach Mills and metal-mouthed scene-stealer Ryan Lee round out the group). On one hand, Abrams had crafted an endearing “Son of Rambow”-style period piece, bottling that childhood thrill of cinematic discovery like so many summer lightning bugs, while at the same time, he feels compelled to turn it into something bigger.

After making mega-successful installments in the “Mission: Impossible” and “Star Trek” franchises, the Paramount golden boy has been granted the freedom to direct his first genuinely original feature, so long as the project in question is capable of delivering the same boffo box office potential. “Super 8″ is refreshing to the extent that it feels personal, but ultimately exasperating for how much the project is compromised by unfair expectations — partly the fault of a hush-hush, fanboy-focused viral marketing campaign that misrepresents a film best suited for today’s teenage filmmakers, the vast majority of whom have never touched celluloid, much less heard of Super 8 film stock.

By virtue of his standing, Abrams is able to assemble a top-shelf team of collaborators, including vfx legend Dennis Muren (“E.T.: The Extra-Terrestrial”), longtime composer Michael Giacchino and d.p. Larry Fong (“Sucker Punch”), though none has contributed his best work: The monster is a disappointment, Giacchino’s score is forgettable and Fong gets distracting lens flares while trying to imitate Allen Daviau’s style.